Conventionally, as transparent electroconductive substrate used in liquid crystal display, organic EL display and the like, glass is used. Recently, there have been demands for its shift to plastic material in light of weight reduction, shatter-proofing property and flexibility. For example, substrates consisting of polyethylene terephthalate, polycarbonate, polyolefin or polyether sulfone has been proposed (for example, see Japanese Patent Application Laid-Open No. 2003-17244).
However, these resin-based substrate materials for display devices have large coefficients of thermal expansion, which are in a range of about 30 to 100 ppm/° C. at 50 to 150° C. If such a material is used to produce a display substrate, difference in thermal expansion between the display substrate and a transparent electrode leads to disadvantages including generation of cracks in the transparent electrode due to changes in the surrounding temperature, resulting in increasing resistance and further generation of disconnection. Therefore, there have been demands for transparent substrates for display devices with small coefficients of thermal expansion.
In Japanese Patent Application Laid-Open No. 10-330534, thermosetting resin containing lamellar clay minerals is disclosed. However, the invention is aiming at improving thermal resistance and mechanical strength, which does not relate to the resin of the present invention having transparency and a small coefficient of thermal expansion.